Spelling in English can be tough sometimes. I usually take it for granted that all my students can spell without any difficulty, but just in case this is not so, have a look at this link to do some revision. Don’t feel shy to repeat after the recording. In fact, that’s the way to improve! ;D
Then get some practice and see how good you are. If you click here you will listen to some sentences where a word is missing.
Enjoy it & good luck!