Question
You want to know discretely what the first way of the three-way handshake is in the context of TCP/IP networking. What is it?
Short Answer
It is the sending of a TCP packet with a flag of "SYN" from the client to the server/destination.
Longer Answer
TCP is used in HTTP communications. TCP uses a three-way handshake; each way has a specific flag in a TCP packet and a specific source and destination (among the two end point devices involved). When a workstation tries to connect to a website (e.g., https://www.continualintegration.com), the workstation sends a TCP packet with a SYN flag to www.continualintegration.com.
The first way is sending a TCP packet with the "SYN" flag (of which several potential flags are possible) to the destination:
Client -----> Server
To read more, see these postings:
https://ddos-guard.net/en/terminology/protocols/tcp-3-way-handshake
https://www.techopedia.com/definition/10339/three-way-handshake
What Is The Second Way of The Three-Way Handshake?
What Is The Third Way of The Three-Way Handshake?