Quick Grammar Lesson: Lie vs. Lay

Lie = to rest horizontally (Past: Lay; Present: Lying)
Lay = to put something in its place (Past: Laid; Present: Laying)

Get it yet?

You can lie down in bed, or you can lay yourself on the bed.

To lay requires an object of sorts.

"I laid my daughter down in bed, tucked her in, and told her a bedtime story."
"I laid the wood on the ground."
"I am laying the books on the counter."

Or you can lie:

"I like to read while lying in bed."
"I am going to lie in the hammock for a while."
"As she lay there sleeping, I continued to read the rest of the bedtime story."*
*This can be confusing, since in this case, "lay" is the past tense of "lie".

I hope this is useful.