>I would prefer visitors entering my sight at index.html
>now I have meta tags only in index.html.
>Should I put them in all pages?
>will it increase the possibility of users entering not from the main page?
If you want the visitors to enter only from the main page, there is no point of putting keywords in all your pages.
Instead you should put in a robot meta tag in order to prevent the subpages from beeing indexed.
You might want to put some keywords in your noframes tag though.
However if you choose to let the engines index all subpages (so people can enter from those) you should put in keywords spesificly related to the subpage content. By optimising each subpage for just a few keywords you will get a higher ranking.
Remember to put up a link to your main page from each subpage if you do this so your visitors dont get stuck.