How to find the Suitable keywords for my website?

Assuming your question is about using A1 Keyword Research for this:

First get some keyword suggestions:
http://www.microsystools.com/products/keyword-research/help/keyword-suggestion-research-tools/

Currently A1KR does not integrate with Google Adwords keywords tool. You should use that to check traffic:
https://adwords.google.com/select/KeywordToolExternal

Then check competition for the keywords:
http://www.microsystools.com/products/keyword-research/help/keyword-research-competition-analysis/

If your question is more general, ask in the search engine optimization forum at this website!