Community-based Open Source Software (OSS) projects are usually self-organized and dynamic, receiving contributions from distributed volunteers. These communities' survival, long-term success, and continuity demand a constant influx of newcomers. However, newcomers face many barriers when making their first contribution to an OSS project, leading in many cases to dropouts. Therefore, a major challenge for OSS projects is to provide ways to support newcomers during their first contribution. In this paper, our goal was to evaluate how the newcomers' perceived efficacy is influenced by the use of an environment that organizes the project information for developers who want to place their first contribution to an OSS project. To accomplish this goal, we created FLOSS coach, a portal aiming to support newcomers to OSS projects, which was implemented based on a model of barriers proposed in previous research. Then, we conducted a study, in which 46 students, split in case and control group, were asked to contribute to an OSS project. We assessed the newcomers' self-efficacy by conducting a questionnaire before and after the assignment. We found that presenting the information according to the model of barriers had a positive influence on newcomers' self-efficacy, empowered the newcomers, making them more confident and comfortable during the contribution process. However, there is also some indication that FLOSS coach did not lower the technical barriers.