// Offset is how many bytes to move
// Offset can be positive or negative
var offset int64 = 5
// Whence is the point of reference for offset
// 0 = Beginning of file
// 1 = Current position
// 2 = End of file
var whence int = 0
newPosition, err := file.Seek(offset, whence)
if err != nil {
log.Fatal(err)
}