SSRS : How to give parameter values in URL Http requests?

Question

I created a dataset in an SSRS report and this dataset uses a parameter. Here is the request:

select { [Measures].[ID Distinct Count]} on COLUMNS,
non empty filter({ [DIM ANESTH].[PBM ANE NOM].[PBM ANE NOM] }, 
not InStr( [DIM ANESTH].[PBM ANE NOM].CURRENTMEMBER.MEMBER_VALUE, 'Unknown') = 1) on ROWS
from BDD_PAT_ANESTH where ( StrToSet(@param_req, Constrained))

param_req is a parameter name I gave, and SSRS created a corresponding report parameter and joined both. Here are some screenshots:

All it works, but I want to call the report server via http requests (in C#), and provide with some parameter values. Usually, SSRS http URLs finish by the parameters : ...&param1=value1&param2=value2 and so on. But I don't see how I can provide with the value "[DIM ANESTH].[ID].&[3]" for example.

An other way could be to define a custom parameter whose values are integers, and to define a second parameter whose origin is the first one and whose values are some members like "[DIM ANESTH].[ID].&[3]".

Do you know how I can achieve either method (I think the first one could be easier).

thank you.

PS: I found this about parameters but it seems to be only partially relevant.

EDIT : @McNets I tried to follow your advice, but with no success: considering the third screenshot, the one with default values, I tried to put in my browser this url :

http://localhost/reportService?%2fSSRS%2fReport6_tryParamFrom0&rs:Command=PDF&param_req=5

and I got this error:

Reporting Services Error Default value or value provided for the report parameter 'param_req' is not a valid value. (rsInvalidReportParameter)

Please see : here from microsoft. What am I missing?

Answer 1

Done. Defining a parameter 'param2' whose values are integers and captions are strings, the point is the MDX query:

select {[Measures].[ID Distinct Count]} on COLUMNS,
  non empty filter({[DIM ANESTH].[ID].MEMBERS  },
  [DIM ANESTH].[ID].CURRENTMEMBER.MEMBERVALUE = @param2 ) on ROWS from BDD_PAT_ANESTH