You can do it in screen the terminal multiplexer.

• To split vertically: ctrl a then |.
• To split horizontally: ctrl a then S (uppercase one).
• To unsplit: ctrl a then Q (uppercase one).
• To switch from one to the other: ctrl a then tab

Note: After splitting, you need to go into the new region and start a new session via ctrl a then c before you can use that area.

EDIT, basic screen usage:

• New terminal: ctrl a then c.
• Next terminal: ctrl a then space.
• Previous terminal: ctrl a then backspace.
• N'th terminal ctrl a then [n]. (works for n∈{0,1…9})
• Switch between terminals using list: ctrla then " (useful when more than 10 terminals)
• Send ctrla to the underlying terminal ctrla then a.