This thesis describes the Peer-to-Peer Application Gridella. The decentralized architecture of P2P systems enables each peer to fulfill search requests solely by local interactions. The system described in this thesis scales to high numbers of peers and data items and remains available in spite of failing peers. Further, probabilities for successful search requests can be given. Gridella is based on the P-Grid approach~\cite{infosysdb:Aberer01a, infosysdb:Aberer02c} and is designed to be compatible with Gnutella `` infiltrate'' the existing Gnutella infrastructure and enable an simple migration. P-Grid increases the efficiency of search requests, and reduces the required bandwidth for system maintenance. On the basis of an analysis of the existing Gnutella infrastructure and its problems I describe the foundations of P-Grid. The developed application supports the existing Gnutella and the new Gridella protocol. Then the architecture and the communication between the systems are described in detail.