Hello there.
Here i have 2 questions.
1. what size can a Avatar picture be and what format Ie: Jpeg, bm, Tiff?
A size of 80x80 pixels works fine. You can use JPGs to reduce the size (there is a size limit of 10kb IIRC). You can use GIFs if your chosen avatar includes transparency, but no animated GIFs; also, the maximum size may not be exceeded.
2. Can i upload pictures straight from my computer? If not how do i get around that?
Thank you for your time.
When writing a post, open "Additional Options" beneath the text window. By "Attach", you may upload images and files attached to the post. Apart from that, you can use an external image hosting service (e.g. Photobucket), get the image URL and use the [IMG] tags (little picture frame button) to insert them into the post.