Whatever the source, the picture should be available on the PC (including Macs, Linux boxes) that you connect to the internet with.

Currently Mountain Views can accept JPEG format pictures. Often pictures in this format are named as "apicture.jpg" or "Pic100-001.jpg", though not always. If your picture is not in JPEG format you will need to convert it to JPEG format which can be done by editing tools such as Paint, Paintshop Pro or Photoshop.
(This picture of Lough Aluirg, Croghnalaragagh and Muckish in Donegal is 400 pixels wide by 259 high )

Final Maximum height: 600 pixels
Final Maximum width: 800 pixels
Final Maximum sum of height and width:  1400 pixels

For example  the following sizes are allowed  
600 high X 800 wide
300 high X 800 wide

You can now upload a picture up to around 50 Megapixels, that is the height times width does not exceed 50 million. In the unlikely event that your picture is larger than this, then resize in a photo editor before uploading or you can use an online tool such as shrinkpictures.com. (If using shrinkpictures.com set the maximum picture size to 2000 pixels). Any picture outside the final maximums above  will be resized to fit. Pictures at or below the maximum size will not be resized.
For best results resize in an editing program which has the added advantage that you may also be able to improve the picture, for example by correcting pictures that have excessive contrast, a notorious issue in upland photography. There is more about improving picture quality later.

Your options therefore are
a. resize the picture and then upload
b. upload as is

Put in a comment - use it to tell us something interesting about the picture. It's often valuable to identify peaks or other larger features that are visible.
Put in the file name of your picture, which will be somewhere available to your PC. Usually it is more convenient to browse to the correct location of the file.  As you put in the file name, a message will appear informing you of the likely delay.
Put in a caption for the photo. (up to 30 characters allowed)

Press "Add record". When uploading a comment with a picture, you can expect a delay as the picture is uploaded from your PC and then a long further delay while the picture is processed at the other end. (The total delay is usually a few seconds with broadband)

That's it. The picture should appear.

If the website cannot handle the picture file you are trying to upload it will issue a diagnostic message to help you correct the problem. For example if you try to upload a file that is not a picture or is a picture of the wrong format (say, a .BMP) then the website will issue a warning. There will also be warnings if the file is too large, too small or has an incorrect extension (must end with ".jpg" or ".jpeg").If you have tried to get it to work and it still fails then please contact the MountainViews administrator at admin -at- mountainviews.ie

If you have uploaded a picture and for some reason find that a change is needed (for example if the wrong picture was uploaded for a given mountain) feel free to contact the MountainViews administrator at admin -at- mountainviews.ie
 

Wait for a day that is totally overcast, or if there is sun wait until the sun is at its highest in the sky. Take a picture a long way away from the mountain, arrange the exposure so the ground is too dark and the sky is too bright (pointing towards the sun helps this), ensure that there is nothing of interest in the foreground or middleground, try to get mist covering the summits, ensure that there are some powerlines or roads clearly visible and near and include some of your out of focus friends in fluorescent jackets leering at the camera from nearby.
 

Mountain View pictures are necessarily small so dramatic slopes, interesting shadows, strong contrasting silhouette or colours will all help. Or a strong story.

Bright sun or very slight overcast light will bring out the colour, texture and shape of the land. Unless there is no choice, don't take pictures without strong light.  Evening or morning sun angles bring out the shape of the mountains.

Circumstances such as light snow covering or a view of mountains peeking above clouds can make a picture great.

Posed pictures generally don't work, but pictures with people doing something can be great.

Cropping a picture to concentrate attention on the interesting parts of a view often transforms a picture.

Learn how to get the exposure for the main area of the picture correct. Remember an area of sky in Ireland is usually 10 times as bright as the same area of ground. Camera exposure meters will often react to this by underexposing for the ground so it comes out dark with little discernible detail. Learn how to avoid this for your camera with whatever you have. If you can afford it get a camera which supports filters. The two most useful filters with a digital camera are "Graduated Neutral Gray" and "Polarising Filter" - both help to control contrast.

All the other basics of camera work are needed. Don't shake the camera, don't point it into the sun, make sure it focuses on what you are interested in. Flash is rarely appropriate on hills.

Realise that at least 95% of your pictures are rubbish and you won't look at them again more than once leave aside anyone else.

Make it easy to take pictures as you are out walking. Opportunism is everything in mountain photography, where the light can change in seconds.