We describe the online summer portion of a quantitative skills bridge program focused on helping students prepare socially and academically for the transition to college. College students are increasingly asked to employ quantitative skills across the curriculum, but students arrive at college with varied preparation. Further, those with the least preparation often encounter other challenges to social belongingness and navigating their institution. In response to these needs, our institution developed a bridge program aimed at students with a broad range of interests -- not just STEM, and the program has a significant focus on community-building as well as strengthening quantitative skills. The six-week summer online portion is followed by a face-to-face fall portion. Here we describe key design aspects of the online portion of the program: program goals and structure, selection and demographics of participants, and resources required to run the program. In addition, we share lessons learned that may be relevant for other institutions considering such a quantitative skills bridge program.