Method ExtractFilePath does include the TrailingPathDelimiter character so you don't need to add it in your string. This means that instead of

Code:
<path name>+'\data\file.bmp'


you would use

Code:
<path name>+'data\file.bmp'


As for the string type returned it is same string type that is the default string type of your development environment (AnsiString in Delphi 7, Unicode string in Delphi 2009 and newer, not sure for FPC/Lazarus thou).

As for you being sorry about your lack of knowledge. Don't be. We all have been in your position once but we learned and so will you.
Just don't be afraid to ask. The main purpose of this community is to help each other.