Besides attending live retreats, you can also watch Bettina ji's teachings on her YouTube Channel.
Bettina Bäumer gives "Retreat Seminars" on various texts of the non-dualist Kashmir Shaiva tradition. She mainly teaches three basic Tantras of the Trika School: the Vijnana Bhairava Tantra, the Paratrisika (with Abhinavagupta's Vivarana commentary) and the Netra Tantra (with commentary by Ksemaraja), as well as texts like the Siva Sutra, the Spanda Karika, and the the Pratyabhijna Hridayam. Besides these, she also teaches mystical Bhakti hymns of Kashmir, such as the Sivastotravali by Utpaladeva, the Stavacintamani by Bhatta Narayana, the Sambapancasika and Stotras by Abhinavagupta.
She follows a certain style in conducting these retreats, basically consisting of two sessions of text study, morning and afternoon, about four hours of meditation, recitation of the hymns and slokas of the texts concerned, besides periods of silence and meditative walks in nature (wherever the surroundings permit).
These Retreat Seminars are given in various places around India and in Europe, notably near her home in Varanasi, in Himachal Pradesh, and in Rishikesh, as well as in Srinagar (Kashmir) itself. They typically will be five days long, though shorter or longer sessions are possible.