First Voices has all sort of online resources to assist you in learning Secwepemcstín.
http://www.firstvoices.com/en/Secwepemc/welcome
Introduction from their website:
Secwepemcstín – The Language of the Secwepemc from British Columbia
Secwepemcstín contains the cultural, ecological, and historical knowledge which includes: values, beliefs, rituals, songs, stories, social and political structures and spirituality of the people. The Secwepemc view all aspects of their knowledge, including language, as vitally linked to the land. This knowledge, passed down to the next generations orally, contained the teachings necessary for maintenance of Secwepemc culture and identity.
As the Secwepemc were given the land; they were also given a language. Language was given to the Secwepemc by the Creator for communication to the people and to the natural world. This communication created a reciprocal and cooperative relationship between them and the natural world which allowed the Secwepemc enabled them to survive and flourish in harsh environments. For example, the Secwepemc receive messages from the animals and birds who tell them when it is time to harvest and gather certain foods and medicines. The cricket will tell the Secwepemc when it is time to catch the salmon.
The language connects the land and the people. The language contains the mental, physical, and spiritual connectedness of the Secwepemc to the land. It protects and maintains all forms of Secwepemc knowledge, It keeps the people whole and connected to the Creator. It maintains the Secwepemc responsibility to the land. The language contains traditional ecological knowledge needed to protect biodiversity and it is used to transmit all forms of knowledge to future generations.