how to convert string into integer

It really depends on the string:

say if you have string "123abc" it could be as simple as Val("123abc") wich will produce 123;
however string "abc123" will result in zero (using Val function) - in this case you 'll need parse it and elliminate all non-numeric chars mfirst'
There is CInt(), CLng() function that may convert numeric strings to Integer/Long...

... however, that is just a tip of an iceberg ... :)