Unfortunately, you also have to take care of transferring the money from sponsor to provider. You can do it in three ways:
If you have your own company, you can just invoice them and pay for the costs. That's probably the simplest way.
If you don't have your own company, ask the local Python community or your friends if they can help with that. If there's a Django/Python Association in your country you can ask them for help as well. If you handle the money transfer through a friend's company, keep in mind that you will most likely have to pay taxes on the money you receive. The amount varies from country to country.
You can also ask sponsors to pay for food/printing directly.
You can use a service like Open Collective that will legally handle money for your event (not free).
Make sure to tell the sponsors when you need the money. Money transfer can take a few days and you will have to pay for some things like printing t-shirts or bags beforehand. Make sure to have all the money in your bank account at least 1-2 weeks before the workshop so you don't get into trouble or have to organize some things last minute.
We have prepared a sample invoice for the PSF. They usually sponsor Django Girls events so it might just be something useful for you. You can also use them as an example of how to create an invoice and what should it contain.
Open the file and choose File > Make a copy. In your invoice, you will have to fill the missing details. This has to be done with special care and attention. You can't make mistakes here because it may result in not receiving money before the event.