good question and not one simple answer.
Does your pattern specify if you should work in garter stitch or in stochinette stitch (or something else)?
"to knit" is ambiguous. it is the action of knitting (no matter what stitches you use) and also "making the knit stitch".
But if your pattern says to knit the first 4 rows I am making an easy guess that it shall all be knit stitches. Then you produce garter stitch.
Even if you contiune in stochinette later, it will not curl up with a border in garter stitch.
so: knit the first 4 rows in knit stitch, then follow your pattern.
Good luck on your new hobby, but be careful: it is addictive (I am depending on my knitting these days, really.)
If you have questions: fire them off at us, we love to help!
PS: to make your attemps on searches easier: it spells "to purl" - not knowing that you might search for videos, instructions or help in vain.