The studio provides a wizard to import a BPEL process with all its dependencies (WSDL and XML schemas).
To do so, click File > Import and select Petals > BPEL.

Then, type in the BPEL URL or click Browse... to select it on your local hard drive.
Eventually, select the project or directory in which the BPEL (and its dependencies) will be imported.

Click Finish to run the import operation.