Gaelle,
You may want to try reading your measured weather data in from a generic text file reader (Type 9 for example). This is easier than trying to create a weather file. Then you could supplement your data with selected outputs from a standard TMY weather data reader (such as for azimuth angle and elevation angle).
If you want to do one step better, you could purchase a weather file for your area over the same time period (AMY) and use a combination of your measured data and their interpolated data. One such service is
http://www.weatheranalytics.com/; there may be equivalents that I'm not aware of.
Best Regards,
Ben Heymer