Well, it should look something like this:
Acls
@loop
print "derp game"
print "press A to begin"
B=button()
If B and #A then goto @start
goto @loop
@start
In direct mode, type SAVE"example then click enter (or find on then bottom screen at the top and click SAVE" then type the program name) to load it later, just do the same but with LOAD" instead of SAVE"