Problem - must do an action before others are allowed

[Uku]

I'm doing a cristmasgame to a competition(one estonian ones) and i need to know,
how do i do so:
1)i come in a room and i cant go away first if i go to stadium and speak there(SANTA) and then go everywhere.
2)cant take(look and gives inventory item)CD from cupboard if not talked to SANTA

one word-how do i do so in AGS i can do or cant when something is done(like if i talk to santa then "thingi "is changed from 0 to 1 and i can talk to someone and take cd and go to different rooms(if thingi is 1 then go to room etc.)

EDIT//not so fast,deadline moved from10 januar to 20 so  its 10 days for me to finish(or start. still only graphic readyBUT 100%)so i wil thak you if jou can post your knowleges in 7 days maximum

thank you!

[Ashen]

From the BFAQ:
Variables & How to use them
GlobalInts: your friend


And from the manual:
if ... else ... statements

Basically, 'thingi' would be a variable, and it's be exactly as you described it - set it to 1 when you talk to Santa (thingi = 1;) and check it before you allow the other actions (if (thingi == 1) ...). You can even use the 'Game - Set variable value' and 'Conditional - If variable is set to a certain value' interactions from the Interaction Editor, if you don't want to use scripting at all.

[Uku]

so ags do have variables!seem they are similiar to GM

thank you for your help