I start with one hero and how can i have more during the game?

There are two spring cards that give one hero each. Is there any other way to get more heroes?

Use the Rally Support order. You get influence, tactics, neutral units, and stuff from your cities. Then the supremacy bonus lets you spend up to 3 influence to draw that many hero cards from the hero deck. You get to choose one and keep it.

Why spend extra influence to draw more heroes when you only get to keep one? It gives you a better chance of drawing a hero that matches your alignment which means it is less likely the hero will desert you.

Also remember you can only have 3 heroes max.

Use the Rally Support order. You get influence, tactics, neutral units, and stuff from your cities. Then the supremacy bonus lets you spend up to 3 influence to draw that many hero cards from the hero deck. You get to choose one and keep it.

Why spend extra influence to draw more heroes when you only get to keep one? It gives you a better chance of drawing a hero that matches your alignment which means it is less likely the hero will desert you.

Also remember you can only have 3 heroes max.

Unless you've got commanders in the Banners expansion- then you can have a max of 3 heroes and 2 commanders (if you have the "Lieutenant General" tactics card which allows a second commander.)