I was just wondering what value do we have to enter in the course selectors before take off ? I saw some videos where CRS 1 and CRS 2 were different. How do I find these values ? During the cruise do we have to change them or do we change them just for the approach ?

You would normally set your 'heading', not 'course', to the runway heading, then fly whatever vectors you are given, or switch to LNAV to get on course.

You would use that if intercepting a radial after takeoff. Example:http://204.108.4.16/.../05761AMERY.PDF I hand flew this yesterday up to cruse witch had two radials leaving SFO for LAX so there I tuned both VORs into each course selection then used the overhead switch to seleced witch one was needed in the captains display witch was shown in the AOA previews prior to the NGX release I believe. http://204.108.4.16/d-tpp/1110/00375PORTE.PDF

Wasn't it possible to just follow your SID with the LNAV button to ge you to your first waypoint ? And other question, when do you set the ADF ? I never use it... :/

Set the NAV1 to the radial of the first course on your departure, EG. If you were flying a LIFFY2A out of EIDW, then your CRS1 would be set to 097 for the DUB VOR. You set CRS2 to the ILS localiser course, in case you need to return to the airfield after take-off. Hope this helps. Capt Rónán O Cadhain.

Wasn't it possible to just follow your SID with the LNAV button to ge you to your first waypoint ? And other question, when do you set the ADF ? I never use it... :/

Yes I could have but what fun is that. On the SFO departure I was using LNAV but still followed the radials in the VOR EFIS mode and only used LNAVs guidance as a secondary source. And not every airport has SIDs so you need some ground guidance from navaids or ATC to get your on course. Nothing wrong with grabbing then yoke and doing it yourself. Just to remind you other systems/methods work just as good as a on board computer with established procedures and some practice. You set the ADF if one is needed, simple as that but I never (99%) really have to.

Ok, thanks for the answer !