Help with picture alignment and possibly thumbnails

Hello

i am trying to find a way to align a picture in the center, using the link that is provided with the 'tricks' , didnt help. From html, i know that you can do with 'align=center' but i seem to have some issues, not sure if it works.

Any ideas?

P.S

I will also be asking for help on thumbnails, if there is any guide (i already found some online websites) especially how to strech, but that is not urgent at the moment :P