Log onto Playchess.com. Under the help menu there is an option 'Query upgrade'.
How to get the most out of Fritz depends on your strength. The 'Friend' mode will automatically adjust to your playing strength. Instead of overtyping a handicap in the popup box it will suggest a handicap for you. If you lose a game then next game it should increase your handicap - if you win it will decrease it (the lower your handicap the better Fritz will play).
If your handicap is higher than 250 you might want to try the 'Handicap and Fun' option (File>New>Handicap and Fun) You can choose a preset character or adjust the features to whatever you want. The biggest effect on playing strength is to adjust the blunder range. Higher blunder range = more blunders from Fritz!
Another option is 'Sparring'. Fritz plays a reasonably good game but it will deliberately make mistakes. If you make the diffculty 'very easy' it will make bigger mistakes! If you check the 'point out wins' box Fritz will flash a red light when it has made a bad move - otherwise you have to stay alert and spot the mistakes yourself!
There aren't any tutorials as such but many of the features are very useful and instructive. Explore the options and you'll find lots of good stuff.
For example, if your stuck for a move, you can ask for a hint (Help>Hint). Switching the 'Spy' option on (Help>Spy) shows what Fritz wants to do next move. The Coach function (Help>Coach is watching) will alert you if you make a mistake and give you the choice of taking the move back.
There's lots of great articles on getting the most out of Fritz on www.Chessbase.com
. Click 'Support' from the menu at the top and browse through the Fritz8 articles (the 'T-notes' are also excellent).
One more thing - you can stop Fritz resigning in bad positions - under Tools>Options click the 'Game' tab and under Resign choose 'never'.