How do you learn symbols and valencies?

Answer 1

You need to learn the symbols for the elements I am afraid. Start using a Periodic Table (see the links below).
You could also learn the valencies but if you know the periodic table and understand why elements appear where they do, you can work out the likely valencies from the positions of the elements in the table - they are where they are for a reason!
You must ask your chemistry teacher to explain this reasoning to you - it should form part of your lessons.

This will help
Group number 1 = Valency 1
group number 2 = valency 2
group number 3 = valency 3
group number 4 = valency 4
group number 5 = valency 3
group number 6 = valency 2
group number 7 = valency 1
group number 8 = valency 0 (noble gases, nonreactive)