What should I fill in if I haven’t take the SAT, ACT and PSAT?

You should not use the Chancing engine until you have a better idea of where you are on the PSAT spectrum.

Seriously, you don't know if you are 1150, 1250, or 1450 or somewhere in between so the chancing engine will not return anything useful to you at this time.

Therefore, I highly recommend that you take some PSAT practice tests available on College Board and then pick an average of those scores to plug into your profile. So if you get say 1260, 1310, 1350, I'd use 1300.

https://collegereadiness.collegeboard.org/psat-nmsqt-psat-10/practice/full-length-practice-tests

Alternatively, you can take the SAT practice tests and put in your SAT score or take ACT practice tests and put in your ACT score.

https://collegereadiness.collegeboard.org/sat/practice/full-length-practice-tests

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjtmIfa0q7uAhXJoFsKHZNLBGoQFjADegQIBBAC&url=http%3A%2F%2Fwww.act.org%2Fcontent%2Fdam%2Fact%2Funsecured%2Fdocuments%2FPreparing-for-the-ACT.pdf&usg=AOvVaw2-mDv788Zg-HmN4--FKTTT

If you feel you bombed them, then open a free account on Khan Academy and that will help you with PSAT and SAT prep.

If you need something more hands-on and comprehensive, I found the SuperTutorTV video course extremely helpful.

Bookwise, the College Panda series and the Official SAT and Official ACT are indispensable.

Good luck.