You are probably having this problem because your images are still Photoshop files. Try saving them as jpegs and see what happens.
Before you change your Photoshop files to jpegs, make sure that you have flattened the image. Flattening the image will merge the layers into one.
Before you flatten the image, you may want to save a copy, just in case you change your mind about an image and wish to alter it. Once you have flattened the image, you won't be able to unflatten it. Try opening up the image you wish to add to your site. Click 'save as', and then select 'jpeg'.
If this still doesn't work, you could try resizing the image, though it may be that there is something wrong with your FTP file manager. If you are with a web host, then perhaps you could send them a query or check through their FAQ to see if there is an answer to your problem.
Before you change your Photoshop files to jpegs, make sure that you have flattened the image. Flattening the image will merge the layers into one.
Before you flatten the image, you may want to save a copy, just in case you change your mind about an image and wish to alter it. Once you have flattened the image, you won't be able to unflatten it. Try opening up the image you wish to add to your site. Click 'save as', and then select 'jpeg'.
If this still doesn't work, you could try resizing the image, though it may be that there is something wrong with your FTP file manager. If you are with a web host, then perhaps you could send them a query or check through their FAQ to see if there is an answer to your problem.