Using the analysis tool within CATIA is pretty easy. You first have to constrain the workpiece - use clamps and other geometrical constrains. Then, set your mesh size. Remember, if the mesh size is very fine, you'll most probably get an error that prevents further computation. I usually start off with coarse mesh and then after subsequent solutions, refine them according to my accuracy needs. The next step is defining loads and pressures and displacement constrains. When you're done with this, press on the Calculate button, and you should get a solution.
There are a lot of buttons hidden underneath the workbench toolbar. So, I'd suggest you to bring them out, and mouse-over those buttons which will give you an idea of what those do. I did mostly load and pressure and acceleration applications on my analysis, but you can do a lot more than that.
Generally speaking, the analysis workbench is similar to ANSYS - you basically go through similar steps to define and solve your models.
I have just finished an intensive course on solid modeling based in CATIA v5. and I really want to get into FEA and stress analysis. I have background in compuational fluid dynamics when i did my master's in mechanical engineering, so i am sort of familiar with the subject. I like to know if anyone could help with a website that gives some sample examples of how the FEA/meshing/stress analysis tool works in CATIA v5. I would really appericate it. thanks.