>How do I convert this code "Selection.MoveLeft Unit:=WdWord, Count:=1, Extend:=wdExtend" to VFP so I won't get error?

Like David said, VFP does not support named parameters.
In this case you can place them separated by commas in the same order.

Also, you can get the constants values through the Object Browser. For Word, you can find them already in sites like the VFP Wiki:
http://fox.wikis.com/wc.dll?Wiki~WordConstants

#DEFINE wdWord 2
#DEFINE wdExtend 1

* then something similar to this:
oWord.Selection.MoveLeft(wdWord, 1, wdExtend)