これ ／ この

Hi. I was wondering what sort of situation would you use これ and which would you use この.

For example if I want to say "This dictionary is...." would I use

1. これじしょは。。。

or

2. このじしょは。。。

Sorry if this is basic but I know この is for a specific thing but in the example I have given how do you know which one to use?

ありがとう

You can see it like "This +noun" vs "This one". So:
この その あの - "this/that/that (over there) + noun"
これ それ あれ - "this one / that one / that one (over there)"
so, in your example, since it's this + noun it should be このじしょは。。。
compare:
このじしょはあかいです。 - "This dictionary is red."
これはあかいじしょです。 - "This (one) is a red dictionary."

Hope that was to any help