did a bit of research. You must be in commissioner mode
AND be the GM of the team for the player you are offering the extension. I tried it for a team i wasn't the GM of and the "offer extension" doesn't show up.
"Sorry still looking for contract extension page. Player showing,tried right clicking but only brought up team roster/stats page. Thanks for any additional info. HT/ "
it's not exactly a page: but a drop down menu you're looking for, on the individual player.
So, be GM of the team/player you want to offer extension. Click on rosters & transaction tab. just highlight the player by having the mouse "hover" on the name (it should turn a color - mine is blue.) (don't actually double click to open his profile), then with the name still highlighted, right click your mouse. You should get a drop down list. About half way down that list should be "offer extension". Click on the link. (The full list should include trade options, short list, trade options, etc.) Hope this helps. Sorry 'bout the incomplete info earlier. This should work, as i just tried it. If it doesn't for you.... hmmm.... i'm at a loss.