Multiple currencies in CRM

Hi,

We currently have One currency defined for our companies, but now we are expanding our application to different regions, and those regions would have different currencies. All the opportunitites that we currently have are in USD. But moving forward we would have opportunties in GBP, CAD etc as well. I wanted to see what steps do I have to take so that it would not effect our current system and dashboards.

I have been reading about the active currencies, exchange rate setup etc. but not sure how to exactly use them. Does anyone have a documentattion or refererence materila that I could read and tells me about what steps are to be considered.