you may be good at something which I'm crap at
I'm crap at මෙන්න මේ වගේ යෙදුම් තමා අපි ඉගෙන ගන්ඩ ඕන..
දැං අපිට මේකෙ තේරුම කියල දෙන්ඩ
මොකද ඩික්ෂනරි වලින් මේව තේරුම් ගන්ඩ බෑ...
ටුවිස්ටඩ් තෑන්ක්ස් bro.
such things are rarely taught in classes mate, you will get the hang of it if you keep chatting in english to somebody, or watch films or tv shows ..etc.
I'm crap here follows the same syntax as Im good..
I'm good = mama hondai
I'm good at playing cricket - mama cricket gahanda dakshai, cricket waladi hondai..
after sometime, you will have a better idea on how these connecting words such as 'at' work.
thnks 
උඹව නං මේ ත්රෙඩ් එකට කොහොමත් ඕන..

Unfortunately I have no idea how else to translate it into sinhala.
මට මේකෙ how else to කියන එක අලුත්..
I don't know how to do it - eka karanne kohomada kiyala danne nehe
I don't know how else to do it - eka karanne wena kohomada kiyala danne nehe.
..sorry, I never learned english in the proper way to be able to teach it to somebody else.

