First time churning

Can you guys please explain what does pushing in mean? How do i tranfer funds from my cap1 or chase/bofa accounts to citi in order to recieve the bonus? It is my first time trying to get bank bonus and i have no idea how to make ach transfer. I ve been trying to transfer using zelle since people say it works to trigger the citi banks bonus hovewer i could barely send total of 300$ by partialy sending it. I saw other people having no issues to use zelle and transfering funds to citi checking. Please i would really appreciate anyone who could help me out.