The view from here

The view from here
 

I was telling her that the view from here is very pretty...

estaba diciendola que la vista desde aquí es muy linda (o lindisima)

o

la decía que la vista desde aquí es muy lindisima

I told her that the view from here is very pretty...

la dije que la vista desde aquí es muy linda...

tell someone something
This verb takes an indirect object (someone) and a direct object (something). So, you need to correct the object pronoun you used for 'her'.

The word 'lindísima' needs an accent.

Native English speakers tend to overuse the continuous form (estaba diciendo). Make sure you actually mean 'currently', or 'in the very process of' when you do use it. The object pronoun would sound better if you place it prior to the verb, just like you did with the other tenses. That said, it isn't wrong to slap it on the end of the gerundio. If you do, the gerundio needs to have a written accent so that proper stress is maintained - estaba diciéndole.

Use capital letters at the beginning of a sentence and proper punctuation at the end. ;)

This is practice, so I moved your thread to the proper forum.

"muy lindísima"

You can say "muy linda" or "lindísima", but "muy lindísima" is not correct.