i'd recommend starting with the simulation tutorials to get a good grasp of how the software works.
then it might be helpful for you to draw a picture that shows what the loading condition is and how the parts will attach to each other. i'm not really following exactly what you're looking for.
also, you didn't really describe what the loading condition is and what you want to learn from the analysis. that is an important part about picking boundary conditions. it would also be good to list out any assumptions you think are inherent in how you want to analyze this case.
if you're looking for some one-on-one help for this analysis, we offer this at hawk ridge systems, contact me at email@example.com to setup a time to talk about it further.
also regarding your assembly, you'll need to put in a pack and go, you only uploaded the sldasm so it can only be viewed in view only mode. (it doesn't have the parts)