I guess your question is how to fit a Curie Weiss law to the M vs. T you obtained. The M vs. T curve is your dc-susceptibility (for small fields); I guess your measurement units are emu. In order to obtain the susceptibility you have to divide by the sample volume (cm^3) and the applied magnetic field (Oe) and multiply by the Avogadro constant and the Bohr magneton. This will give you the unit less dc-susceptibility. When you fit the inverse you can obtain the effective moment and the asymptotic paramagnetic Curie temperature.

Thank you Matthias Frontzek sir. Actually Sir I have  M vs T curves of ZFC FC .  Would you please help me out how to get the susceptibility vs T? If any reference also you can give then it will be helpful.

Well, the ZFC-FC vs. T measurements already gives you the susceptibility. Now depending of the material you are characterising then they could be different procedures to process the data depending on the material. For example, for molecular materials you simply multiply your moment (emu) by the molecular weight of your sample and divide it by the sample mass and the applied field. This will give the susceptibility in emu/mol units. For magnetisation you have to multiply the response (emu) per the molecular weight of your compound and divide it by the amount of sample used during the measurements and also by 5585 (to convert to Bohr magnetons). For non-molecular materials, also you can obtain the susceptibility by dividing your sample response by the amount of sample employed during the measurement and the applied field.

Thank you Eufemio Moreno Pineda Sir. 

 Thank you Alak Kumar Majumdar Sir. It would be nice of you if you can send me some reference relating these concepts.

Thank you Alak Kumar Majumdar Sir. This is very useful to me.