File Saving Capabilities

I noticed that there is no real Save functionality within Aspose.Tasks. How do I go about editing a file and then saving it under the same filename, or how do I add a task and then save the file under the same filename? Currently, I am using a .mpp file, do I have to use some other extension in order to be able to use this functionality?

You can read projects in mpp, mpx and xml formats but save it in mpx or xml formats only.

What I am trying to do is edit a particular field of a task and then save the file. However, I get errors whenever I try to save the file because it says it is being used. I need to be able to save the file under the same name that I opened it. Any suggestions?