How to do the question above, I will also need to delete the old image.

Below find the delete area of the function, this does not delete the file.

string OldIMGId = memb.MemberProperties.Find(x => x.Alias == "profilePic").Value.ToString();
            if (OldIMGId != null && OldIMGId != "") 
            {
                _mediaService.Delete(Umbraco.Media(OldIMGId));
            }

Below find the update image bit, 'pic' is HttpPostedFileBase type, memb is an umbraco MemberProfile type.

        var media = _mediaService.CreateMedia(pic.FileName, folder.Id, "Image");
        media.SetValue(Constants.Conventions.Media.File, pic);
        _mediaService.Save(media);

        memb.MemberProperties.Find(x => x.Alias == "profilePic").Value = media.Id;
        Members.UpdateMemberProfile(memb);

Could someone explian how to do this please?