How will the report be executed? For example, will it be run on a client desktop, from e-business suite, etc.?
Nonetheless, there are some steps you must take.
First, create a user parameter – make it a meaningful name (e.g., p_projectnumber)
Second, in your data model query, you can reference that parameter value (e.g., WHERE pa_projects_all.name = :p_projectnumber). This is how you user the parameter value.
To get the parameter value assigned, this is where you have to look at the way the report is called. If you are running the report from the client workstation, create a parameter form and add the parameter to the form. Then, when the report is run, the user is prompted for the parameter.