Try using imageshack.us to upload your pictures because eventualy you'll run out of space to uploading them to GTP itself. Post them using the "Thumbnail 1 or 2" links.
To post them in the competitions around GTP, just post in one of competition's threads in the Photomode Competitions forum! Just make sure you read the rules to the competitions thorughly before you do because some may ask you to have a preview and main picture in one post, or some may just be drifting pictures etc.
Also, try to type a little better, it's in the AUP.
AUP
No slang words that promote laziness, ie; "r", "u", "plz", etc. will be tolerated. Decent grammar is expected, including proper usage of capital letters. Repeated violations will be grounds for suspension and/or permanent removal from the forums.