Cardarine (GW) is usually stacked with Andarine (S4) and osta (mk2866).
Read - https://www.isarms.com/cardarine-gw-501516
https://www.isarms.com/andarine-s4
At 20, taking dbol won't give you much of results except bloating. Don't use steroids at 20, best choice for your is SARMs - https://www.isarms.com/sarms
You need to do a PCT for sarms - https://www.isarms.com/mini-pct-for-sarms-cycles
Weight gain and goals are variable from person to person.
Strength gains also variable.
You need N2Guard and HCGenerate both.