If I buy tickets for tubing session, do I need to buy lift tickets also? Or one covers the other one? I don't know how it works.

That is correct the tubing ticket and ski lift ticket are 2 different and separate purchases

Please somebody can help me!!! I can't buy a tickets for tubin. Can give me the good website? Please

Correct, they are completely separate tickets

Tickets for tubing and skiing are seperate