There are different approaches possible but the easiest would best to simply
use Application.FollowHyperlink
Application.FollowHyperlink "PathandFilename"
Application.FollowHyperlink "C:\temp\test.xls"
If your path is on your form in a textbox named txtXLSFile for example then
youd do something like
Application.FollowHyperlink me.txtXLSFile
For more info lookup FollowHyperlink in the help.