Before you add an image, make sure that it is the correct size and shape for your web page, and that the file size is optimized for the web. If you put an image with a very large file size into a wiki page, it will take a long time for users to download it. Many image editing programs will allow you to compress images for the web.
Go to Wiki.
Select the Wiki tool from the site Tool Menu.
Select Edit.
Select Edit to open the wiki page.
Add image.
Select the Image icon in the editor toolbar to add an image from Resources.
Select the image from Resources.
Select the Select link for the image file if it is already in Resources.
If the image file is not already in Resources, select Add > Upload Files in the Add drop-down menu to drag and drop or browse for and select the file you want.
Select Continue.
Select Continue to complete the image upload.
Preview content. (Optional)
Select the Preview tab at the top of the editing area to view the image in the wiki.
Select Save.
Select Save to save changes.