I will create all type of diagrams for you . Sequence diagrams, class diagrams,Use case diagrams and activities diagrams,etc...
I will just need the understanding of your system or just SRS ,specification doc or your system.
Also your DB Design and class design would be required if the software is already built .
Developing a software program is very complex task, but if do it in the right way while following the available tools, it become much easier. I am good in UML diagrams, Use case diagrams and class base diagrams, also in Data flow diagram. That helps the developers for developing the right and accurate software.