How to read keywords from Excel sheet and to execute them?

Check out the following topic:

Using the DDTDriver Object to Retrieve Data From Excel Files

While it does not do the specifics of translating UFT stuff to TestComplete, it shows how to build a DDT loop using an Excel sheet and processing information accordingly.  This is your starting point, really. In the example given, you would replace the ProcessData sub with whatever code you would need to write to execute your keyword. My guess is that it would be something like a large extended Select Case block where each keyword read in from the Excel would be parsed through as a case and, for each case, a different function is called.