Which framework can be used to develop cross-platform applications?

Im doing this last minute and literally none of my neighbors or people that my dad works with use excel so if anyone could me make up an example

The open systems interconnection (osi) reference model: defines standards for many aspects of computing and communications within a network. is a generic description for how computers use multiple layers of protocol rules to communicate across a network. defines standards for wireless local area network (wlan) communication protocols. details the advantages and disadvantages of various basic network cabling options.

How to do this programming flowchart?