If you don't know already then I wouldn't do it. But... if you must solder your own motherboard, you need to desolder the stubs out of there. With a fine soldering tip heat the solder while holding the stub with a pair of needle-nosed pliers. gently pull on the stub while heating so it's removed as quickly as possible. You don't want to use more heat than necessary. Next, and quickly, remove the liquid solder using a "Solderpult" which can be bought for around $15 at Radio Shack or similar stores. A proper "suck" will remove all the solder around where the stub was and leave the hole empty of solder as well. Repeat for the other stub and check both sides of the board to ensure the majority of the solder is gone. Be careful not to let the solder smear or run across other leads.
Replacing the capacitor should be straight forward at this point if you know how to solder. If you aren't entirely comfortable with this procedure, and the motherboard is going to be expensive to replace, then I'd have an expert do it. Such a simple operation should be inexpensive.
-- Ah sh*t! sys64738 --