Consider a network which consists of noiseless point to point channels. In this network, the source node wants to send messages to a specific set of sink nodes. If an intermediate node v has just one input channel then the received symbol by that node can be replicated and sent to the outgoing channels from v. If v has at least two incoming channels then it has two options. It can either send the received symbols one-by-one, one symbol in each time unit, or v can transmit a combination of the received symbols. The former choice takes more time compared to the latter option, which is called network coding. In the literature, it has been shown that in a single source finite acyclic network the maximum throughput can be achieved by using linear network codes. Significant effort has been made to efficiently construct good network codes. In addition, a polynomial time algorithm for constructing a linear network code on a given network was introduced. Also an algorithm for constructing a linear multicast code on an acyclic network was introduced. Finally, a method for finding a representation matrix for the network matroid of a given network G was also introduced. This matrix can be used to construct a generic code. In this thesis we first provide a review of some known methods for constructing linear multicast, broadcast and dispersion codes for cyclic and acyclic networks. We then give a method for normalization of a non-normal code, and also give a new algorithm for constructing a linear multicast code on a cyclic network. The construction of generic network codes is also addressed. / Graduate / 0984 / 0544 / esmaeili@uvic.ca