Hi Ron,
I'm not sure what you mean by 'access' in your question.
To receive mail from both accounts, click 'Send/Receive'.
To receive mail from one account only, click the little arrow next to 'Send/Receive' and select the relevant account.
To send mail by your default account, simply click 'New Mail' (or select from your Contacts list).
To send mail from a different account, still use 'New Mail' (or your Contacts list) but then click in the 'From' field and select the relevant account.
To change your default account, go to Tools > Accounts > Mail. Highlight the relevant account and click on 'Set as Default', followed by 'Close'.
Well, I've tried to think of everything you could mean by 'access' but, if I've misunderstood your meaning, just post again.
Chris