How to update a field by adding a value to the existing value?

[eluser]toopay[/eluser]
i'll do that this way :

+------------------+
| players_table |
+------------------+
| id |
| name |
| team_id |
+------------------+

+------------------+
| goals_table |
+------------------+
| id |
| minutes |
| player_id |
| home_team_id |
| away_team_id |
| match_date |
+------------------+

With this db structure, i can get single result and grouped result (goals at a match or total goals) for every player in 'players_table'. Everytime player 'A' make a goal, i'll insert one row at 'goals_table' related with player 'A'.