VBA transfer data from one workbook to another

how would i go about transferring data from one workbook to another? the starting data is in:

workbook: "VEF LOGBOOKm working.xlsm"
worksheet: "Finished"
cell: b1


I need it to go to the first unused cell in column a in:

workbook: "VEF SUMMARYm.xlsm"
worksheet: "Batch Data"
cell: a?


everything i have tried i am getting runtime, and google searches are coming up too complicated for my purposes. thank you for any help