Hi and welcome to the forum.
I see that you seem to have no clue about Switzerland, right? This is not to turn you down, au contaire!, but to explain a few things:
In contradiction to other countries where several national parks exist, Switzerland has only one National Park, to be found in the Far East+ of the country, a region where Raeto-Romansh, the fourth official language of Willy Tell's own country is spoken. It has a much different meaning than a national park in the US or in other countries. Everything is protected here, no trees may be felled, neither flower picking nor hunting nor leaving the trails are allowed, no construction work can be done, the only exception is the road that is leading across. The intention is to give nature back its original look. As a consequence, you can find a lot of rare animals there, it's a hiker's paradise where guided tours are offered. You find it in a side valley of the Engadine , the second longest valley in Switzerland. The Engadine is one of the four best known tourist areas of the country (besides famous +Bernese Oberland+, the +Valais+ and +Ticino ). I suggest to stay up there for the entire lenght of your intended visit, you won't regret it, take this for granted. Search for village names like Scuol-Tarasp, Schlarigna/Celerina, Samedan, St. Moritz, Puntraschigna/Pontresina, Segl-Maria and attractions like Diavolezza, Corvatsch, Muottas-Muragl. There are hundreds of km of sign-posted trails to be found in the region, from easy to difficult ones. Make sure to get accommodation soon as July will be peak season.
Altitudes are given in meters, not in km, by the way. The lower part of the Engadine valley is around 1'200 m, the higher part around 1'800 m, whereas the side vallleys lead much higher up; the surrounding mountains can reach altitudes of up to 4'000 m.
Any more questions? Feel free to ask, it's a pleasure to assist.