Attaching user to comment

How would I attach as user to the form input being added into the db?
User name is defined as @current_user in application.rb

def comment

@albums = Albums.find(params[:id])
@albumscomment =
Albums.find(params[:id]).comments.create(params[:comment])

    if request.post? and @albumscomment.save
    flash[:notice] = 'comment submission succeeded!'
    redirect_to :action => 'show', :permalink => @albums.permalink
    end

end

def comment
@albums = Albums.find(params[:id])
@albumscomment =
Albums.find(params[:id]).comments.create(params[:comment])
@albumscomment.username = @current_user
   if request.post? and @albumscomment.save
         flash[:notice] = 'comment submission succeeded!'
         redirect_to :action => 'show', :permalink => @albums.permalink
   end
end