Michèle Campeau 

Michèle Campeau said:

What is the best way to create a project for an external client is locally – create project?

Yes.  Create a project.

Michèle Campeau said:

How can I add the client’s translation memories into my Trados version. How do we add a server – what is the name of the server – what is the port?

Let's break this down a bit so we know what you actually have?  What you been provided with by your client?  If you are connecting to their server (GroupShare most likely) then they will provide you with these details as this will be their server and not ours.

Michèle Campeau said:

I have files I need to translate (3 letters) coming from the client as well as the client’s translation memory. How do I send the translation of the 3 letters back to the client? What is the best way to send the translation back to a client once the documents have been translated?

I suggest you start by reading the documentation provided in Trados Studio first.  I'm sure you'll get some help if you get stuck, but I think you'll get more from this if you have been through the basics first.  So look in the welcome view and you'll see under the "Get Started" tab some very useful guides that should answer all the questions you have raised so far... an more!